1. Field of the Invention
This invention relates to film flaw detection systems including means for detecting film thickness variations caused by foreign material on the film, metallized cue tabs on the film, or burnt spots, for example, and means for detection of sprocket hole or sound track flaws.
2. Description of the Prior Art
Film flaw detection systems utilizing electric sensing elements or photoelectric measurement devices have been previously known. Such systems have often relied upon speed or coincidence signals as part of the detection means. In addition, such systems, while desirable, are subject to a higher failure rate than the present capacitance system due to breakage of crystals and the like. Also, prior systems have had less sensitivity than the present capacitance system in that feelers used in the present system can have a smaller mass than in the prior art devices.